Multiple spool valve assembly



Nov. 9, 1965 H. H. SCHMIEL 3,216,443

MULTIPLE SPOOL VALVE ASSEMBLY Filed March 11, 1963 2 Sheets-Sheet 1 INVENTOR.

HERBERT H. SCHMIEL ATTORNEYS.

Nov. 9, 195 H. H. SCHMIEL 3,216,443

MULTIPLE SPOOL VALVE ASSEMBLY Filed March ll, 1963 2 Sheets-Sheet 2 INVENTOR.

HERBERT H. SCHMIEL 3,216,443 Patented Nov. 9, 1965 3,216,443 MULTIPLE SPOOL VALVE ASSEMBLY Herbert H. Schmiel, Willoughby, Ohio, assignor to Parker- Hannifin Corporation, Cleveland, Ohio, a corporation of Ohio Filed Mar. 11, 1963, Ser. No. 264,121 8 Claims. (Cl. 137-269) The present invention relates generally as indicated to a multiple spool valve assembly for controlling the operation of a corresponding number of fluid motors.

Hitherto, it has been necessary to provide a variety of differently cored valve housings for correspondingly different fluid circuits. Thus, for two well-known basic fluid circuits, that is, the so-called parallel circuit (any one or more or all valve spools of the assembly may be operated at will to control the respective fluid motors) and the so-called series-parallel circuit (only one valve spool at a time may be operated to control its respective fluid motor), it has been prior practice to provide two vastly different housings. Further modifications in a three-spool valve assembly, for example, would include connection together of first and second spools in parallel for operation independently or simultaneously and connection of the third spool in series-parallel to said first and second spools, whereby the third spool can be operated only when the first and second spools are in neutral position. In known multiple spool valve assemblies of this character, the housings for the different circuits have vastly different coring arrangements thus making it costly with reference to the different patterns and cores that must be provided and making its costly insofar as stocks and inventories are concerned.

Accordingly, it is a principal object of this invention to provide a simplified coring arrangement for multiple spool housings which enables a single housing to be made up for parallel, series-parallel, or other connection of multiple spool valves.

It is another object of this invention to provide a housing for a multiple spool valve assembly as aforesaid which readily can be converted from one type of operation to another.

Other objects and advantages of the present invention will become apparent as the following descri tion proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

FIG. 1 is a cross-section View of a multiple spool valve assembly according to the present invention, such section having been taken substantially along the line 11, FIG. 2;

FIG. 2 is a side elevation view as viewed from the right-hand side of FIG. 1;

FIG. 3 is a cross-section view taken substantially along the line 3-3, FIG. 2, showing the coring arrangement for the housing to provide for series-parallel operation;

FIG. 4 is a cross-section view corresponding to FIG. 3, except illustrating modification of the housing to provide for parallel operation;

FIG. 5 is a crosssection View also corresponding to FIG. 3 showing yet another modification of the housing to provide for parallel operation of two spools and seriesparallel operation of the third spool with respect to the first two spools; and

FIG. 6 is a fragmentary cross-section view illustrating a reconversion plug arrangement whereby to enable reconversion of the FIG. 4 arrangement to that of FIG. 5, or of the FIG. 4 or FIG. 5 arrangements to the seriesparallel operation of FIG. 3.

Referring now in detail to the drawings, and first to FIGS. 1 and 2, the multiple spool valve assembly 1 is herein shown by way of example as comprising three four-way open center valve spools 2a, 2b, 2c reciprocable in parallel bores 3a, 3b, 3c in the unitary housing 4 for controlling a corresponding number of double acting fluid motors 5a, 5b, 50.

As well-known in the art, the three spool bores 3a, 3b, 3c are each intersected axially therealong starting at the middle thereof by a central wishbone bypass passage 6 which communicates the inlet port 7 with the tank port 8 when all three spools 2a, 2b, 2c are in neutral position as shown in FIG. 1; by a pair of pressure feed passages 9a, 9b, 9c that are alternately communicated with the inlet port 7 via bypass 6 in a manner to be described; by a pair of motor passages 10a, 10b, 10c connected with the respective fluid motors 5a, 5b, 5c; and by a pair of tank passages 11 common to all spool bores 3a, 3b, 30 which alternately communicate the adjacent motor passages 10a, 1012, or with the common tank port 8.

The housing 4 is provided with yet another bore 12 which is parallel to the spool bores and which intersects the inlet port 7 for mounting of a relief valve'assembly 14 therein. In the present case, the relief valve assembly 14 is of the pilot operated type in which, when the pressure in the inlet port 7 and in the chamber 15 behind the main relief valve member 16 exceeds the force exerted by the spring 17 against the pilot valve member 18 causes the latter to be forced away from its seat to bleed the fluid from the chamber 15 into the left tank passage 11 faster than fluid can be replenished through the main valve orifice 19, whereupon the pressure in the inlet port 7 acting on the area of the main valve member 16 forces it away from its seat against spring 20, whereby excess pressure in the inlet port 7 is released through the seat member 21 into the right tank passage 11.

For simplifying the drawing and description, all three valve spools 2a, 2b, 2c are shown as being of identical form, namely, four-way open center type for causing the pistons in the respective fluid motors 5a, 5b, 50 to be operated in one direction or the other in response to shifting of the respective spools 2a, 2b, 2c in one direction or the other from the neutral positions shown in FIG. 1. To that end, each spool 2a, 2b, 20 has alternate lands and grooves, and is held in the neutral position of FIG. 1 by the spring centering mechanism 23 associated with one end thereof. When all of the spools 2a, 2b, 2c are in neutral position, fluid delivered to the inlet port 7 as by a pump, not shown, flows through the common bypass passage 6 and through the tank port 8 to a fluid reservoir or tank, not shown, and the pistons in the respective motors 5a, 5b, 5c are held in whatever positions they happen to be because of blocking of fluid communication between the mot-or passages 10a, 10b, 10c and the pressure feed passages 9a, 9b, 9c and the tank passages 11.

To the extent that the coring of the housing 4 is illustrated in FIG. '1, it is exactly the same in all of the modifications shown, the sole differences being in the plane 33 on which the FIGS. 3, 4, and 5 are based, and these differences are in drilled passages for conversion of the FIG. 3 housing to that of FIG. 4 or FIG. 5, as desired.

Referring first to FIG. 3, which shows the basic coring in plane 33, the passages 6e, 92, 10a and 11e are lateral extensions of the respective wishbone portions of bypass 6 upstream of the respective spool bores 3a, 3b, 3c, of the respective pressure feed passages 9a, 9b, 9c, of the respective motor passages 10a, 10b, 10c, and of the tank passages 11. These sets of passages 6e, 9e, lfle, and lie are intersected by stepped bores 25a, 25b, 250 in which are disposed respective check valve bodies 26a, 26b, 260 provided with packing rings to prevent fluid communication between the adjacent pressure feed passage extensions 9e and motor passage extensions 102, and between the motor passage extensions 1% and the adjacent tank passage extensions lle, and to prevent external leakage from the respective tank passage extensions lle. Movable in each check valve body 26a, 26b, 26c is a check valve member 27a, 27b, 270 which is urged by a spring 28 (see left valve body 260, FIG. 3) to close fluid communication between the bypass passage extension 62 and the adjacent pressure feed passage extension 9e, except when the bypass 6 is closed downstream thereof, whereupon pressure bulids up in the inlet port 7 and in the bypass passage extension 62 to unseat the check valve member 27a, 27b, or 270 to feed fluid under pressure to the pressure feed passage 9a, 9b, or 90 via extension 9e and thence to the adjacent motor passage 10a, 10b, or 10c upon operation of the associated spool 2a, 2b, or 2c to an operating position.

The FIG. 3 embodiment of the housing 4 as originally cored and finished, provides for series-parallel operation, that is, only one valve spool 2a, 2b, or 2c may be operated at a time since the bypass 6 from which it receives fluid under pressure must be open upstream thereof. Thus, the third spool 20, when shifted from neutral position to one of its operating positions closes the aforesaid bypass 6 and in order for pressure to build up in the bypass 6 and associated extension 6e which communicates with the upstream portions of bypass 6, spools 2a, and 2b must remain in neutral position. Similarly, if the second spool 2b is shifted from neutral position to one of its operating positions, the first spool 2a must at that time be in neutral position so that fluid under pressure may build up in the inlet port 7 and in the associated portion 6e of the bypass 6 which is immediately upstream of the second spoo'l 2b.

In the arrangement depicted by FIGS. 1 and 3, when any one of the spools 2a, lb, or 2c is shifted toward the right from the FIG. 1 position, the left pressure feed passage 9a, 9b, or 96 is placed in communication with the left motor passage 10a, 10b, or 100, whereupon fluid under pressure flows from the inlet port 7 through the associated left check valve member 27a, 27b, or 27c to move the piston in the associated fluid mot-or a, 5b, or 5c in one direction. At the same time, the right motor passage a, 10b, or 10c is communicated with the right tank passage 11 for flow of displaced fluid through tank port 8 to a suitable tank or reservoir. On the other hand, when any spool 2a, 2b, or 20 is shifted toward the left from neutral position, the right pressure feed port passage 9a, 9b, or 90 is in fluid communication with the associated right motor passage 10a, 1%, or 100 whereby fluid flows from the inlet port 7 and bypass passage 6 and extension 6e through the associated check valve member 27a, 27b, or 270 to cause the piston in the associated motor 5a, 5b, or 5c to be moved in the opposite direction with fluid displaced from the motor flowing to the tank port 8 via the left motor passage 10a, 10b, or 100 which is now in fluid communication with the left tank passage 11.

The check valves 27a, 27b, 27c herein serve as load checks to prevent load dropping, or back flow of fluid in case the fluid pressure in the inlet port 7 is less than in the associated pressure feed and motor passages 9a, 9b, 9c and 10a, 10b, 10c.

Referring now to FIG. 4, it is to be noted that the coring of the housing 4 is exactly the same as in FIGS. 1 and 3, and the only thing that has to be done to provide for a full parallel circuit wherein the spools 2a,

2b, 2c may be operated independently or simultaneously any two or three at a time. To make such conversion from series-parallel as shown in FIG. 3 to parallel as shown in FIG. 4, there is formed, as by drilling, a hole 30 which extends between the pairs of bypass passage extensions 6e and bores 31a, 31b, 310 from the check valve bores 25a, 25b, 25c intersecting hole 30. Inserted in each bore 31b and 310 is a sleeve member 32b, 32c which constitutes a seat for the associated check valve member 27b, 27c and which isolates the associated bypass passage extension 6e from both the bore 30 and the adjacent pressure feed passage 9e. Accordingly, the extensions 6e for spool 2a, and the bore 30 (via bores 31a and sleeve members 32b and 320) become an inlet passage for feeding fluid under pressure from the inlet port 7 to the pressure feed passage extensions 9e for operation of the respective spools 2a, 2b, 2c, either independently, or simultaneously with one or two of the others. The bore 30 is closed as by threaded plug 33.

Considering the operation of the first spool 2a, when it is operated, the bypass 6 through it is closed and pressure builds up in one or the other of the bypass passage extensions 6e to supply fluid under pressure to one or the other of the pressure feed passages 9a (via 9e and check valve member 27a therein) to cause actuation of the fluid motor 5a in one direction or the other. Such pressure, through openings 31a, also builds up in the bore 39, but if neither the second nor third spools 2b, 2c are operated, the check valve members 27b, 270 are not open. However, when the second or third spools 2b, 2c are operated independently, or while the first spool 2a is operated, the associated spool bypass 6 is closed and the resulting pressure buildup in the bore 30 unseats the appropriate check valve member 27b or 270 to supply fluid under pressure for operating the associated motor 5b or 50 in one direction or the other. Accordingly, in the FIG. 4 arrangement which is a parallel arrangement, the three spools 2a, 2b, 2c can be operated one at a time, any two at a time, or all three at a time, by the simple expedient of merely providing the drilled hole 30 and the cross bores 31a, 31b, 31c of which the second and third ones viz, 31b and 31c have tubular inserts 32b and 32c therein.

In the arrangement shown in FIG. 5, the first and second spools 2a and 2b are in parallel arrangement by providing the bore 30 which extends between the bypass extensions 6e of the first and second spools 2a and 2b and again drilling through as at 31a, 31b, and providing the tubular inserts 32b which may be identical in structure and function to those described in relation to FIG. 4. The check valve bores 250 for the third spool 2c are left exactly as they were in FIG. 3. In this arrangement the first and second spools 2a and 2b may be operated independently or simultaneously, but since the third spool receives fluid under pressure only from the bypass 6 and bypass extensions 6e, it can be operated only when the first and second spools 2a and 2b are in neutral position with the common bypass 6 open so that fluid under pressure Will build up in the inlet port 7 and in the bypass passage 6 up to the third spool 20 for flow through the selected check valve member 27c.

As shown in FIG. 6, the FIG. 4 parallel circuit can be reconverted or changed to the FIG. 5 circuit'simply by providing plugs 40 in place of the sleeves 32a to seal off the bypass passage extensions 62 with the bore 30, and to provide seats for check valve members 270 between the bypass passage extensions 6e and the respective pressure feed extensions 9e, said plugs 40 having openings 41 for flow of fluid from 6e to 9e. Going a step further, the FIG. 5 arrangement then can be reconverted back to FIG. 3 by providing plugs 40 in association with the bores 31b and with enlarged bores 31a. Of course, the FIG. 4 arrangement similarly may be reconverted to the FIG. 3 arrangement by using the plugs 40 in place of sleeves 32b and 32c and in enlarged bores 31a. Furthermore, by

selective use of the plugs 40 and sleeves 32 the FIG. 4 arrangement, for example, can be such that the first and third spools 2a and 2c may be operated in parallel one or both at a time, but with the second spool 2b operative only when the first spool is in neutral position. Numerous other arrangements can obviously be provided.

In summary, therefore, it can be seen that the present invention requires the making of only one basic housing casting 4 which has the same coring regardless of the ultimate circuit arrangement, whether series-parallel, parallel, or a combination of them. Thus, castings 4 can be made for stock or inventory, and finished to the extent shown in FIGS. 1 and 3, whereupon assembly may be readily completed for FIG. 3 series-parallel operation, or quickly and easily converted for parallel and other operation simply by drilling or boring holes and 31a, 31b and/or 310 and installing the tubular inserts 32b and/or 32c. Moreover, the provision of plugs 40, or in fact, plugs in the drilled hole 30, the housing 4 may be reconverted.

Although in the foregoing example, all three spools 2a, 2b, 2c are of the four-way open center type, it is to be understood that one, two, or three three-way spools may be substituted for operating a corresponding number of single acting fluid motors with one of the motor ports plugged or left undrilled. Likewise, one or more of the spools may be of the four-way float type which has in addition to the two operating positions provided in the four-way spools here shown, another operating position, a so-called float position in which the motor ports are placed in fluid communication with one another and with a tank port (usually with restricted communication to build up some pressure but at the same time to preclude cavitation of the motor, as when the piston therein floats or moves toward its rod end.)

If weight saving is of any importance the hole 30 may be provided in housing 4 as cast and left open at its lower end if finished as in FIG. 3. However, if the housing 4 is finished as in FIGS. 4 or 5, the lower end of cored hole 30 need only be counterbored and tapped for the plug 33, and the openings 31a, and 31b and/or 31c provided for sleeves 32b and/or 320.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A housing for a spool valve assembly having (a) at least two spool bores for reciprocation of valve spools therein,

(b) a bypass passage intersecting both spool bores and adapted for connection with a fluid pressure source and with a fluid reservoir at its respective ends,

(c) pressure feed passages intersecting the respective spool bores and having extensions communicating with said bypass passage upstream of the respective spool bores,

(d) motor passages intersecting the respective spool bores for connection with fluid motors, and

(e) return passages intersecting the respective spool bores leading to the pressure end of said bypass passage,

said housing further having additional passages connecting the pressure end of said bypass passage with at least one pressure feed passage of the downstream spool bore, and at least one sleeve means inserted in one of said additionalpassages operative to isolate the pressure feed extension of said downstream spool bore from said bypass passage except through said additional passages, whereby valve spools in said spool bores may be selectively operated one at a time or simultaneously to control the respective motors.

2. The housing of claim 1, further including another spool bore downstream of said first two spool bores for reciprocation of another valve spool therein, said bypass passage also intersecting said another spool bore, at least one other pressure feed passage intersecting said another spool bore and having an extension communicating with said bypass passage upstream of said another spool bore, at least one other motor passage intersecting said another spool bore for connection with another fluid motor, and said return passage also intersecting said another spool bore, whereby valve spools in said first two spool bores may be operated either selectively or simultaneously as aforesaid, but a valve spool in said another spool bore may be operated only when the first two spool bores are inoperative.

3. The housing of claim 1, further including another spool bore downstream of said first two spool bores for reciprocation of a valve spool therein, said bypass passage also intersecting said another spool bore, at least one other pressure feed passage intersecting said another spool bore and having an extension communicating with said bypass passage upstream of said another spool bore, at least one other motor passage intersecting said another spool bore for connection with another fluid motor, said return passages also intersecting said another spool bore, wherein said additional passages also connect the pressure end of said bypass passage with the pressure feed passage of said another spool bore, a sleeve means is inserted in one of said additional passages operative to isolate the pressure feed extension of one of said downstream spool bores from said bypass passage except through said additional passages, and a removable plug means is inserted in another of said additional passages operative to block fluid communication between said additional passages and the pressure feed extension of the other of said downstream spool bores, whereby valve spools in the upstream spool bore and in the downstream spool bore which has an isolated pressure feed passage as aforesaid may be either selectively or simultaneously operated, While a valve spool in the other downstream spool bore may be operated only when the other two spool bores are inoperative.

4. A spool valve assembly comprising a housing having (a) at least two parallel spool bores for reciprocation of valve spools therein,

(b) a bypass passage intersecting both spool bores and adapted for connection with a fluid pressure source and with a fluid reservoir at its respective ends,

(c) pressure feed passages intersecting the respective spool bores and extending laterally therefrom to lateral extensions of said bypass passage upstream of the respective spool bores,

(d) motor passages intersecting the respective spool bores for connection with fluid motors, and

(e) return passages intersecting the respective spool bores leading to the end of said bypass passage that is adapted for connection to a fluid reservoir,

a valve spool reciprocable in each spool bore from a neutral position whereat fluid flows through said bypass passage from one end to the other and fluid communication between said pressure feed and motor passages and between said return and motor passages is blocked thereby to an operating position whereat said bypass passage is blocked thereby and said pressure feed and motor passages are in fluid communication via the respective upstream extensions of said bypass and pressure feed passages for flow of fluid under pressure therethrough; said housing, laterally of said spool bores, being provided with additional passages intercommunicating the end of said bypass passage that is adapted for connection with a fluid pressure source with said lateral extension of the pressure feed passage of the downstream spool bore, and sleeve means in one of said additional passages operative to isolate the pressure feed passage extension of the downstream spool bore from its associated bypass passage extension, whereby said spools may be selectively operated either one at a time or simultaneously.

5. A spool valve assembly comprising a housing having at least two parallel spool bores which are intersected axially therealong starting from the middle by (a) a bypass passage having a pair of lateral extensions upstream from the respective spool bores, said bypass passage being adapted for connection with a fluid pressure source and with a fluid reservoir at its respective ends,

(b) pairs of pressure feed passages having upstream lateral extensions straddling the respective pairs of bypass lateral extensions,

(c) pairs of motor passages straddling the respective pairs of pressure feed passages for connection with fluid motors, and

(d) a pair of return passages common to both spool bores straddling the respective pairs of motor passages and leading to that end of said bypass passage that is adapted for connection with a fluid reservoir,

said housing, laterally of said spool bores, having connecting passages between said bypass lateral extensions and the adjacent pressure feed lateral extensions, valve spools selectively reciprocable in the respective spool bores from a neutral position whereat said bypass passage is open successively via said spool bores from one end to the other, and said motor passages are blocked thereby from the adjacent pressure feed and return passages, to at least one operating position whereat said bypass passage is closed thereby and one of said motor passages is intercommunicated with the adjacent pressure feed passage via the upstream lateral extensions of the associated feed and bypass passages, said housing, between the pairs of bypass lateral extensions, being provided with passage means which are in communication with only one pair of said bypass lateral extensions, and are in communication with both pairs of pressure feed lateral extensions, communication between the other pair of bypass lateral extensions and said passage means being blocked by sleeve means disposed in said passage means adjacent said bypass lateral extensions, said sleeve means also blocking communication between said other pair of bypass lateral extensions and the associated pressure feed lateral extensions, whereby said spools may be operated selectively or simultaneously, as desired.

6. A multiple spool valve assembly for controlling operation of a corresponding number of fluid motors, comprising a housing having an inlet port for connection with a fluid pressure source, a return port for connection with a fluid reservoir, and motor ports for connection with said fluid motors; at least two spool bores in which there are disposed valve spools selectively reciprocable in said housing to control operation of the respective motors; said housing having at least one pair of passages extending from each of said spool bores, one of said passages of each pair being in communication with a motor port upon movement of its associated valve spool to an operative position, the other passage of each pair being in communication with said inlet port upstream of the respective spool bores via a bypass passage leading from said inlet port to said return port and intersecting said spool bores, each pair of passages having a connecting passage therebetween for flow of fluid therethrough from said inlet port to the motor port of the selectively operated spool, said housing also including a first passage, a second passage communicating said first passage with the pair of passages associated with the upstream spool bore, and a third passage communicating said first passage with the passage of said other pair which is in communication with the motor port upon movement of its valve spool to an operative position as aforesaid, and means blocking communication between the passages of said other pair and also between said first passage and the passage of said other pair which is in communication with the inlet 8 port, whereby said spool may be operated selectively or simultaneously.

7. The method of converting a series-parallel housing for a multiple spool valve assembly to a parallel housing, such series-parallel housing being of the type which includes an inlet port for connection with a fluid pressure source, a return port for connection with a fluid reservoir, and motor ports for connection with fluid motors, at least two spool bores in which there are disposed valve spools selectively reciprocable in such housing to control operation of the respective motors, such housing having one pair of passages extending from each of the spool bores, one of the passages of each pair being in communication with a motor port upon movement of its associated valve spool to an operative position, the other passage of each pair being in fluid communication with the inlet port upstream of the respective spool bores via a bypass passage leading from the inlet port to the return port and intersecting the spool bore, each pair having a connecting passage therebetween for flow of fluid therethrough from the inlet port to the motor port of the selectively operated spool; comprising the steps of providing a first passage in the housing adjacent such pairs of passages, interconnecting such first passage with the pair of passages associated with the upstream spool bore, interconnecting the first passage with the passage of the other pair which is in communication with its associated motor port upon movement of its valve spool to an operative position as aforesaid, and blocking communication between the passages of the other pair and between the first passage and the passage of such other pair which is in fluid communication with the inlet port.

8. The method of converting a parallel housing to a series-parallel housing, such parallel housing being of the type which includes an inlet port for connection with a fluid pressure source, a return port for connection with a fluid reservoir, and motor ports for connection with fluid motors, at least two spool bores in which there are disposed valve spools selectively reciprocable in the housing to control operation of the respective motors, such housing having a pair of passages extending from the respective spool bores, one of the passages of each pair being in communication with a motor port upon movement of its valve spool to an operative position, the other passage of each pair being in communication with the inlet port upstream of the respective spool bores via a bypass passage leading from the inlet port to the return port and intersecting the spool bores, each pair having a connecting passage therebetween for flow of fluid therethrough from the inlet port to the motor port of the selectively operated spool, such housing also including a first passage, a second passage communicating the first passage with the pair of passages associated with the upstream spool bore, and a third passage communicating the first passage with the passage of the other pair which is in communication with the motor port upon movement of its valve spool to an operating position as aforesaid, and sleeve means blocking communication between the passages of the other pair and between the first passage and the passage of the other pair which is in communication with the inlet port; comprising the steps of blocking the third passage and providing a connecting passage between the other pair of passages.

7 References Cited by the Examiner UNITED STATES PATENTS 3,000,397 9/61 Schmiel 137-596.13 3,077,901 2/63 Klessig 137596.l3 3,106,065 10/63 Stacey 137625.69

M. CARY NELSON, Primary Examiner.

HENRY T. KLINKSIEK, Examiner. 

1. A HOUSING FOR A SPOOL VALVE ASSEMBLY HAVING (A) AT LEAST TWO SPOOL BORES FOR RECIPROCATION OF VALVE SPOOLS THEREIN, (B) A BYPASS PASSAGE INTERSECTING BOTH SPOOL BORES AND ADAPTED FOR CONNECTION WITH A FLUID PRESSURE SOURCE AND WITH A FLUID RESERVOIR AT ITS RESPECTIVE ENDS, (C) PRESSURE FEED PASSAGES INTERSECTING THE RESPECTIVE SPOOL BORES AND HAVING EXTENSIONS COMMUNICATING WITH SAID BYPASS PASSAGE UPSTREAM OF THE RESPECTIVE SPOOL BORES, (D) MOTOR PASSAGES INTERSECTING THE RESPECTIVE SPOOL BORES FOR CONNECTION WITH FLUID MOTORS, AND (E) RETURN PASSAGES INTERSECTING THE RESPECTIVE SPOOL BORES LEADING TO THE PRESSURE END OF SAID BYPASS PASSAGE, SAID HOUSING FURTHER HAVING ADDITIONAL PASSAGES CONNECTING THE PRESSURE END OF SAID BYPASS PASSAGE WITH AT LEAST ONE PRESSURE FEED PASSAGE OF THE DOWNSTREAM SPOOL BORE, AND AT LEAST ONE SLEEVE MEANS INSERTED IN ONE OF SAID ADDITIONAL PASSAGES OPERATIVE TO ISOLATE THE PRESSURE FEED EXTENSION OF SAID DOWNSTREAM SPOOL BORE FROM SAID BYPASS PASSAGE EXCEPT THROUGH SAID ADDITIONAL PASSAGES, WHEREBY VALVE SPOOLS IN SAID SPOOL BORES MAY BE SELECTIVELY OPERATED ONE AT A TIME OR SIMULTANEOUSLY TO CONTROL THE RESPECTIVE MOTORS. 